Dipolar-glass-like relaxor ferroelectric behaviour in the 0.5BaTiO_3-0.5Bi(Mg_(1/2)Ti_(1/2))O_3 electroceramic

摘要

In this study, the dielectric and ferroelectric switching behaviour of 0.5BaTiO_3-0.5Bi(Mg_(1/2)Ti_(1/2))O_3 (BT-BMT) ceramics are investigated. The BT-BMT ceramic exhibits a typical dipolar-glass-like, dielectric polarisation relaxation. This is attributed to the 15 distinct possible local A_4B_2 configurations around the O ions and the effect this unavoidable local compositional variability has on the dipole relaxation behaviour of inherent 1-D <111> dipole chains, arising from correlated off-centre displacements of Bi~(3+) and Ti~(4+) ions along local <111> directions. On the other hand, switchable polarisation under strong applied electric fields is observed on different length scales accompanied by the appearance of strong polarisation relaxation, as observed via time-delayed piezoresponse hysteresis loop measurements. These experimental results demonstrate that this BT-BMT ceramic is relaxor ferroelectric in nature, although it exhibits dipolar-glass-like dielectric relaxation behaviour.